I left out the remnants of my Long Island Iced Tea. This was a mixture of various liquors, lemon juice, Splenda, and water from the melted ice. It was left on my kitchen counter for several days:

You'll notice the bottom of the glass has a pattern:

To the naked eye, it appears fractured. I had initially thought my glass was shatterred. It even has crevasses like you'd see on a glaciar. Here's an extreme closeup of the center:

Presumably the water evaporated away, and the syrupy alcoholic remains formed a residual solid. What is the name of the process that causes it to produce such a fasicinating, complex, and irregular pattern? It seems somehow related to crystalization, but I can't account for this given my simple understanding of that process (I understand crystalization as an additive phenomenon, where molecules are attaching together to form a complex shape. This, on the other hand, appears more the opposite of that.)

2 Answers
2

Your instincts are right -- this is indeed crystallisation. Your original cocktail was a solution of lots of non-volatile components (sugar, Splenda, citric acid from the lemon juice, and many many other things...) in some rather more volatile solvents (ethanol and water). Only a limited amount of any of the non-volatile compounds can dissolve in a given volume of solution. So as the volatile compounds evaporated, your solution gradually became saturated, then a little super-saturated, and then finally the non-volatile components started to crystallise out in the patterns you show.

In general slow evaporation of a solvent is quite a common method of crystal growth, e.g., for X-ray diffraction studies.

I'd be very surprised if this was crystal formation. It looks to me as if the goo at the bottom of the glass formed a film, then as the film dried it shrank and fractured. The pattern of lines you're seeing are stress fractures in the film not crystals.

The fracture pattern looks very symmetrical, but then you have a circular boundary condition due to the edge of the cocktail glass. Igamine you had a pizza that had been cut into slices, then imagine the pizza shrinks away from the centre. The slices would separate from each other and you'd be left with a similar pattern of radial cracks.